New ground measurements made by the West Antarctic Global Positioning System (GPS) Network (WAGN) project suggest the rate of ice loss of the West Antarctic ice sheet has been overestimated.

Don’t start celebrating just yet, however—West Antarctica is still losing significant amounts of ice, only at a slightly slower rate than some recent estimates suggested. According to Ian Dalziel, lead principal investigator for WAGN, "Antarctica is contributing to rising sea levels. It is the rate that is unclear."

Antarctica was once buried under a deeper and more extensive layer of ice during a period known as the Last Glacial Maximum. About 20,000 years ago the ice began thinning and retreating. As the ice mass decreases, the bedrock immediately below the ice rises.

Eighteen GPS transceiver stations were installed on bedrock outcrops across West Antarctica. Precise three-dimensional locations of the stations were determined during measurements made from 2001 to 2003 and from 2004 to 2006. The difference in the positions during the two time periods indicates the motion of the bedrock.

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The WAGN project is noteworthy because is the first time researchers have directly measured the vertical motion of the bedrock at sites across West Antarctica using the US Global Positioning System.

The results should lead to more accurate estimates of ice mass loss and a more complete model of bedrock movements in the region.

The findings will appear in the electronic journal Geochemistry, Geophysics, Geosystems of the American Geophysical Union and the American Geochemical Society.

The WAGN project was performed by a team from The University of Texas at Austin's Jackson School of Geosciences, The Ohio State University's School of Earth Sciences, and The University of Memphis' Center for Earthquake Research and Information.

Information for this article was provided by Science Daily, the University of Texas. And the National Science Foundation.